An animation of a point source emitting circular wave fronts. The source moves from left to right across the field of view superposed with the motion of the emitted wave fronts. Time elapsed, source and cursor coordinates are also displayed along with two radio buttons allowing one to choose a Classical or Relativistic situation. The source speed is adjustable from zero to twice the wave speed in ?classical? mode and from zero to 0.99 the wave speed in Relativistic mode.
There are no technical issues reading with Explorer 5.0. The animation appears to be rather bullet proof and works fine under all possible parameter choices. It is difficult for Macs to run.
Identify Major Learning Goals:
To illustrate the wavelength shift caused by the Doppler Effect for a moving source and the creation of shock fronts as the source speed becomes greater than the wave speed.
Target Student Population:
Lower Level Undergraduate
Prerequisite Knowledge or Skills:
The elementary acquaintance with concepts of wave motion, in particular the idea of a wavelength.
Content Quality
Rating:
Strengths:
Intuitive display of the physical effect.
Concerns:
None
General Comments on Quality: This is a simple animation that does a good job at illustrating a focused concept. Introduction of the Doppler shift and the onset of the shock front regime in the introductory class beg to have an animation illustrating the usual derivations and this animation does it in the obvious way without any complications obscuring the essential details.
Potential Effectiveness as a Teaching Tool
Rating:
Strengths:
Recommended Use(s) for Material (used for Effectiveness Review): Lecture/Demo, Homework, just-in-time exercise
This animation would be very effective as an illustration during the presentation of the usual Doppler shift material of a typical introductory class at any level. The concept is clearly presented and the wavefronts are generated at a rate that effectively demonstrates the effect.
Concerns:
It will probably not be clear to introductory students that while the classical option is valid for classical waves in general, the relativistic option is only valid for light waves in a vacuum nor does it address situations that would normally produce Cerenkov radiation.
Ease of Use for Both Students and Faculty
Rating:
Strengths:
The application is very easy to use. The graphics are simple and to the point and the function controls are clearly identified and intuitive to use. This applet can be hosted locally and customized according to individual taste by a user knowledgeable in the scripting of Physlets.
Concerns:
There is no reset button allowing you to start the animation over. Currently you have to deduce the need to toggle the radio buttons to perform a reset or use the ?refresh? capability of your browser.
General Comments on Usability: Parameters can be changed on the fly, which is a nice touch. For large classroom display purposes a user may desire to re-script the applet for larger display. Information on how to script Physlets is described in the book Physlets: Teaching Physics with Interactive Curricular Material by Christian and Belloni.
Creative Commons:
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